|[pic] |1.3.5 Practice: DNA and Heredity |
| |Practice Assignment |
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| |Biology Sem 2 (S2598061) |
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If the parent cell is diploid, the daughter cells will also be diploid.
d) What are the four steps of mitosis, in order? Hint: The acronym PMAT gives you the first letter of each step, in order. (1 point)
Prophase: the chromosomes darken and become more defined, the nucleic envelope breaks down
metaphase the Sister chromatids meet up in the MIDDLE. (m for middle and metaphase)
anaphase: the pairs move APART (a for apart and anaphase)
telophase: the new cells begin to develop
2. a) How does meiosis introduce genetic variation into offspring? Think about how the chromosomes line up.(1 point)
1 by crossing over in prophase I , 2 , by indpendenent assortment and three by mutations in S phase
b) How do the products of meiosis compare to the original cell? Think about chromosome number. (1 point)
Meiosis results in four daughter cells (gametes) which have half the number of chromosomes of the original cell. They are therefore called haploid cell
c) Why are there two sets of phases during meiosis, but only one during mitosis? Think about what is different about meiosis and mitosis. (1 point)
Mitosis is the cell cycle for somatic cells which are diploid (2n).
Meiosis is the cell cycle for germ cells (gametes) where they are haploid (n) so that is why they have two sets of phases.
3. a) A plant can have either tall (T) stems or short (t) stems. Two plants are crossed. One has the genotypeTt and the other has the genotype Tt. Fill in the Punnett square below for this cross. (1 point)
b) What is the genotype ratio for this cross? (1 point)
The genotype ratio will be 1 TT : 2 Tt : 1 tt
c) What is the phenotype ratio for this cross? (1 point)
The phenotype ratio will be 3 tall stems : 1 short stem
d) Two different plants are crossed. One has the genotype tt and the other has the genotype Tt. Fill in the Punnett square below for this cross. Remember, one parent allele goes in each space on the top and...